Well treatment



Sept. 29, 1959 A. M. sHooK 2,906,338

WELL TREATMENT Filed Nov. 27, 1957 United lStates Patent WELL TREATMENT Austen M. Shook, Houston, Tex., assigner to Texaco Inc., a corporation of Delaware Application November 27, 1957, Serial No. 699,304 Claims. (Cl. 166-15) This invention relates to a method and apparatus for the treatment of wells. In accordance with one embodiment this invention relates to the gravel packing of wells. In accordance with another embodiment this invention relates to an operation, and apparatus suitably employed in conjunction therewith, wherein a well is gravel packed and, if desired, fractured in substantially the same operation.

In the production of petroleum from a petroleum producing formation one difliculty sometimes encountered, particularly when the petroleum producing formation is an unconsolidated formation, is the productivity of the well becomes reduced after a period of time due to the sanding up or plugging of the well. To avoid this reduction in well productivity due to a well sanding up it has been proposed heretofore to gravel pack a well. In a gravel packing operation a filter bed of porous granular material is deposited Within the Well bore adjacent the petroleum producing formation. This porous gravel bed tends to support the adjacent petroleum producing formation and tends to prevent the well from sanding up due to the transport of nely divided solid material from the producing formation into the Well bore.

Recently it has been proposed, see patent application Serial No. 401,159 iiled December 30, 1953, now U.S. 2,814,347, the disclosures of which are herein incorporated and made part of this disclosure, to carry out a gravel packing and formation fracturing operation substantially simultaneously. The operations disclosed therei-n, however, are complicated and require the use of a rather large amount of equipment and production tubing or conduit.

It is therefore an object of this invention to provide an improved method of Well treatment.

It is another object of this invention to provide an improved method of effecting gravel packing and formation fracturing substantially simultaneously.

Another object of this invention is to provide an improved method of gravel packing a well.

Still another object of this invention is to provide an improved method and apparatus suitable for use inpressure gravel packing a well.

Yet another object of this invention is to provide an improved well completion assembly or apparatus.

How these and otherobjects of this invention are accomplished will become apparent in the light of the accompayning disclosure made with reference to the accompanying drawing which schematically illustrates one embodiment of the practice of this invention particularly useful for carrying out a combination well gravel packing and fracturing operation. In at least one embodiment of the practice of this invention at least one of the foregoing objects is accomplished. p

In accordance with this invention it has now been discovered that an improved well completion operation is obtained by disposing a well screen or liner within a well bore adjacent a petroleum producing formation and then carrying out a subsequent gravel packing operation Patented Sept. 29, 1959 ICC via the production tubing. The production tubing, after completion of the well treatment or gravel packing operation, is then employed to carry the produced petroleum from the resulting treated formation.

Referring now in detail to the accompanying drawing which schematically illustrates a practice of this invention as directed toa well treatment operation involving gravel packing in combination with formation fracturing, a well bore 11 is provided with a casing 12. As illustrated in the drawing, the casing 12 terminates within well bore 11 above the petroleum producing formation 14. Provided within casing 12 is production tubing 15. Attached, desirably rotatably attached or threadedly engaged to the lower end of tubing 15, is a slotted well screen or liner 16 which is disposed within well bore 11 adjacent the petroleum producing formation 14. As illustrated in the accompanying drawing, that portion of the well bore below the end of casing 12 is open hole. A fluid-tight packer 18 is provided within the annulus between tubing 15 and casing 12.

A closure 19 attached to or iitted into the lower end of tubing 15 is disposed between tubing 15 and liner 16 effective to prevent direct liuid communication between the interior of well screen 16 and the interior of tubing 15. Tubing 15, above closure 19 and below packer 18, is provided with a discharge orifice 20, such as a standard side door choke which can be operated (opened and closed) by a wire line, for the discharge of liquid or an admixture of liquid and granular material from the interior of tubing 15 into the annular space between tubing 15 and well screen 16 and well bore 11 and/or casing 12. As illustrated in the accompanying drawing, discharge orifice 20 is provided with a spring loaded ball 21 contained Within a spider housing 22 effective to permit the discharge of liquid and gravel from the interior of tubing 15 but also effective to prevent the ow of iluid or a mixture of fluid and granular material from the aforesaid annular space into the interior of tubing 15.

A wire line opening is provided in the upper end of tubing 15 through which runs wire line 24 which has attached to its lower end a closure breaker orweight 25. Also in fluid communication with the upper end of tubing 15 is production conduit 26 for the introduction ofiluid or mixture of liquid and granular material into tubing 15 or for the production or delivery of liquid petroleum from formation 14 via tubing 15.

In an operation in accordance with the practice of this invention wherein a petroleum producing formation is gravel packed a mixture of carrier liquid and granular material, such as sand or finely divided gravel, is introduced via production conduit'26 into tubing 15. This mixture is ydischarged from tubing 15 via discharge coni therefore becomes lled with liquid, the granular material remaining outside within the annular space since it is too large -to pass through the slots or perforations of,

well screen 16. Further, since closure -19 is interposed between well screen 16 and tubing 15 flow of carrier.

liquid up through the tubing 15 is possible. Pressure, by suitable means such as a pump (not shown), such as uid pressure exerted by liquid ifilling tubing 15, is then The interior of Well screen l16, sincev o* exerted upon the liquid filling the interior of well screen 16 and its surrounding annular spacesuflicient to force at least a portion of the mixture of carrier liquid and granular material therein into the surrounding petroleum producing formation.

Desirably the pressure exerted-upon the mixture within the annular space surrounding well screen 16 is suflicient to fracture the petroleum producing formation. When a fracture occurs at least a portion of the mixture of carrier liquid and granular material is forced into the formation and granular material deposited within the resulting fracture. Suflicient pressure may be. exerted upon the mixture within the annular space to enlarge the resulting fracture 21 to any desired extent.

Since the interior of well screen 16 and the annular space surrounding the Well screen 16 are in direct fluid communication substantially the same fluid pressure would exist within the well screen interior and the-annular space; Further, it is pointed out that since the pressure exerted upon the mixture within the annular space surrounding the well screen is fluid pressure derived from suitable pressuring means, such as al pump located at the surface, not illustrated, via production conduit 26 and tubing 15, the pressure differential across closure 19 will be at a substantially low value, approaching zero. Further, with packer 18 positioned as described hereinabove the pressure within the annular space against the petroleum producing formation 14 is readily maintained and exerted substantially exclusively against the producing formation 14 undergoing treatment.

When the formation has been gravel packed, and desirably fractured, such that there remains a residue or bed of the granular material within the annular space defined by the well screen 16 and the adjacent petroleum producing formation 14 the pressure exerted upon the mixture within the annular space is removed. Thereupon wire line 24 carrying closure breaker 25 is caused to descend or fold to mechanically rupture or break closure 19. When this occurs the interior of well screen 16 is now in direct fluid communication with the interior of tubing 15. Production of petroleum from the resulting treated formation 14 is then resumed, the petroleum being produced through the gravel pack now occupying the annular space between the well screen 16 and adjacent formation 14, through well screen 16 and upwardly through the interior thereof through tubing and recovered at the surface via production conduit 26. It is mentioned during these production operations that discharge orifice is closed by` spring loaded ball 21 operating within the spider housing 22.

Although in the embodiment illustrated in the drawing the closure 19 is illustrated to be mechanically ruptured or broken by means of weight 25 suspended on wire line 24, various suitable means may be employed to rupture closure 19. These methods include placement of a suitable explosive in close proximity to closure 19 and exploding the same to rupture closure 19. This explosive may be located with respect to closure 19 by means of wire line 24. Another method of effecting rupture of closure 19 would be to chemically attack closure 19 by means of a chemical agent, such as an acid, e.g. hydrochloric acid, sulfuric acid, nitric -acid and the like, effective to chemically dissolve closure y19. In this embodiment closure 19 would be fabricated from a material readily attacked by the acid employed, e.g., brass, copper, zinc, etc. If desired, a strong base, such as sodium hydroxide or caustic soda, might be employed in which event an alkali-attacked metal, such as aluminum, should be employed for the fabrication of closure 19.

Still another method of effecting rupture of closure 19 would be to place in contact with closure 19 a sufcient amount of a solvent suitable to effect dissolution of the closure. Various solvents Vmight be employed depending upon the material employed to fabricate closure 19. For example, an organic solvent, such asa mixture of acetone and ether, might be employed when-closure mad@ 0f nitrocellulose, or benzene or other highly aromatic solvents might be employed when closure 19 is fabricated from a bituminous material,A such as tar.

Although the drawing shows the well bore 11 penetrating the petroleum producing formation 14 to be an open hole it is pointed out that the practice of this invention is applicable to a cased formation wherein the petroleum producing formation is provided with a perforated casing and the like. When the petroleum producing formation is provided with a perforated casing the mixture of granular material and carrier liquid is forced into the petroleum producing formation via the perforations in the casing and the fluidpressure exerted through these perforations is sulllcient to fracture said formation.

Various fluids may be utilized as the carrier liquid employed in the gravel packing operations in accordance with the practice of this invention. These fluids include the normally liquid hydrocarbons, crude petroleum, lease crude, petroleum fractions, diesel oil or kerosene, lease crude or petroleum fractions such as diesel oil or kerosene thickened with a suitable thickening or gelling agent such as sodium palmitate (Napalm) and the like. Aqueous liquids such as water, thickened or unthickened with additives which increase the viscosity thereof and reduce fluid loss, as well as brines, such as formation'brines, might be suitably employed as a carrier liquid in a gravel packing operation in accordance with this invention.

As will be apparent to those skilled in the art many modifications, changes and alterations are possible in the practice of this invention without departing from the spirit or scope thereof.

I claim:

1. A method of treating a well in which a well screen is disposed in the well boreopposte the petroleum producing formation to provide an annulus between said well screen and said formation, the interior of said screen being in fluid communication with said annulus, said well screen being attached at the upper end thereof to a tubing within said well bore, said tubing being provided therein with a closure at about the position where said well screen is attached to said tubing effective to prevent direct fluid communication between the interior of said tubing and the interior of said well screen, which comprises introducing into said annulus a mixture of granular material and a liquid in an amount at least sufficient to occupy said annulus, directing fluid under pressure tothe mixture in the annulus and to the interior of the screen so as to `exert a pressure on said liquid within said annulus sufficient to force some of said mixture comprising liquid and granular material into said formation while at the same time maintaining substantially the same fluid pressure within the annulus during the aforesaid pressuringzoperation, leaving within said annulus granular material to form a filter pack between said formation and' said screen and removing said closure between said screen and said tubing so as to provide directllluid communication between the interior of said screen and said tubing.

2. A methodin accordance with claim l wherein said mixture of granular material and liquid is introduced into said annulus via said tubing through a valved opening provided in said tubing'above said closure and-wherein the pressure differential across said closure between said tubing and said screen is substantially Vzero.

3. A method in accordance with claim l wherein the pressure exertedl on said mixture in said annulus is sufficient to fracture said formation.

4. A method in accordance with claim 1 wherein said closure is removed by mechanically rupturing'said closure.

5. A method in accordance with claim 1 wherein said closure is removed by chemically attacking said closure to effect dissolution of said closure.

6. A method in accordance with claim-1 wherein said suitable solvent.

than

7. An apparatus suitable for use in well completion which comprises a tubing, a well screen attached at its upper end to the lower end of said tubing, a closure positioned within said tubing above said well screen effective to prevent direct fluid communication between the interior of said tubing and the interior of said screen and a llow control orice provided within said -tubing above 'said closure adapted for the discharge of uid from the interior of said tubing.

8. A well completion assembly comprising a tubing, a well screen 4attached to the lower end of said tubing, a closure disposed within said tubing between said tubing and said screen effective to prevent direct uid communication between the interior of said screen and the interior of said tubing, ow discharge means provided within said tubing above said closure and adapted for the discharge of fluid from the interior of said tubing to the outside thereof and a production packer surrounding said tubing above said discharge means, said production packer being adapted to make a fluid type seal about the outside of said tubing.

9. A method of treating a well in which a Well screen is disposed in the well bore opposite the petroleum producing formation to provide an annulus between said screen and said formation, the interior of said screen being in fluid communication with said annulus, said well screen being attached at the upper end thereof to a tubing within said well bore, said tubing being provided therein with a closure at about the position where said well screen s attached to said tubing, effective to prevent direct uid communication between the interior of said tubing and the interior of said well screen, which comprises introducing into said annulus a mixture of granular material and a fracturing liquid in an amount at least sucient to occupy said annulus, said fracturing liquid being in contact with said formation, exerting a pressure upon said mixture in said annulus sufficient to fracture said formation and to force some of said mixture into said formation, the fluid pressure within the interior of said well screen and said annulus during the aforesaid fracturing operation being substantially the same, removing said closure and producing petroleum from the resulting treated formation via said well screen and tubing, the produced petroleum flowing from the interior of said screen directly into the interior of said tubing.

10. A method in accordance with claim 9 wherein said fracturing liquid comprises a liquid hydrocarbon and wherein said granular material is sand.

References Cited in the le of this patent UNITED STATES PATENTS 2,207,334 Reynolds et al. July 9, 1940 2,217,215 Coberly Oct. 8, 1940 2,349,062 AUren May 16, 1944 2,359,302 Curtis Oct. 3, 1944 

1. A METHOD OF TREATING A WELL IN WHICH A WELL SCREEN IS DISPOSED IN THE WELL BORE OPPOSITE THE PETROLEUM PRODUCING FORMATION TO PROVIDE AN ANNULUS BETWEEN SAID WELL SCREEN AND SAID FORMATION, THE INTERIOR OF SAID SCREEN BEING IN FLUID COMMUNICATION WITH SAID ANNULUS, SAID WELL SCREEN BEING ATTACHED AT THE UPPER END THEREOF TO A TUBING WITHIN SAID WELL BORE, SAID TUBING BEING PROVIDED THEREIN WITH A CLOSURE AT ABOUT THE POSITION WHERE SAID WELL SCREEN IS ATTACHED TO SAID TUBING EFFECTIVE TO PREVENT DIRECT FLUID COMMUNICATION BETWEEN THE INTERIOR OF SAID TUBING AND THE INTERIOR OF SAID WELL SCREEN, WHICH COMPRISES INTRODUCING INTO SAID ANNULUS A MIXTURE OF GRANULAR MATERIAL AND A LIQUID IN AN AMOUNT AT LEAST SUFFICIENT TO OCCUPY SAID ANNULUS, DIRECTING FLUID UNDERPRESSURE TO THE MIXTURE IN THE ANNULUS AND TO THE INTERIOR OF THE SCREEN SO AS TO EXERT A PRESSURE ON SAID LIQUID WITHIN SAID ANNULUS SUFFICIENT TO FORCE SOME OF SAID MIXTURE COMPRISING LIQUID AND GRANULAR MATERIAL INTO SAID FORMATION WHILE AT THE SAME TIME MAINTAINING SUBSTANTIALLY THE SAME FLUID PRESSURE WITHIN THE ANNULUS DURING THE AFORESAID PRESSURING OPERATION, LEAVING WITHIN SAID ANNULUS GRANULAR MATERIAL TO FORM A FILTER PACK BETWEEN SAID FORMATION AND SAID SCREEN AND REMOVING SAID CLOSURE BETWEEN SAID SCREEN AND SAID TUBING SO AS TO PROVIDE DIRECT FLUID COMMUNICATION BETWEEN THE INTERIOR OF SAID SCREEN AND SAID TUBING. 